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+/*
+ * Copyright © 2018 Ebrahim Byagowi
+ * Copyright © 2018 Google, Inc.
+ *
+ * This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Google Author(s): Behdad Esfahbod
+ */
+
+#ifndef HB_AAT_LAYOUT_TRAK_TABLE_HH
+#define HB_AAT_LAYOUT_TRAK_TABLE_HH
+
+#include "hb-aat-layout-common.hh"
+#include "hb-ot-layout.hh"
+#include "hb-open-type.hh"
+
+/*
+ * trak -- Tracking
+ * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6trak.html
+ */
+#define HB_AAT_TAG_trak HB_TAG('t','r','a','k')
+
+
+namespace AAT {
+
+
+struct TrackTableEntry
+{
+ friend struct TrackData;
+
+ float get_track_value () const { return track.to_float (); }
+
+ int get_value (const void *base, unsigned int index,
+ unsigned int table_size) const
+ { return (base+valuesZ).as_array (table_size)[index]; }
+
+ public:
+ bool sanitize (hb_sanitize_context_t *c, const void *base,
+ unsigned int table_size) const
+ {
+ TRACE_SANITIZE (this);
+ return_trace (likely (c->check_struct (this) &&
+ (valuesZ.sanitize (c, base, table_size))));
+ }
+
+ protected:
+ HBFixed track; /* Track value for this record. */
+ NameID trackNameID; /* The 'name' table index for this track.
+ * (a short word or phrase like "loose"
+ * or "very tight") */
+ NNOffsetTo<UnsizedArrayOf<FWORD>>
+ valuesZ; /* Offset from start of tracking table to
+ * per-size tracking values for this track. */
+
+ public:
+ DEFINE_SIZE_STATIC (8);
+};
+
+struct TrackData
+{
+ float interpolate_at (unsigned int idx,
+ float target_size,
+ const TrackTableEntry &trackTableEntry,
+ const void *base) const
+ {
+ unsigned int sizes = nSizes;
+ hb_array_t<const HBFixed> size_table ((base+sizeTable).arrayZ, sizes);
+
+ float s0 = size_table[idx].to_float ();
+ float s1 = size_table[idx + 1].to_float ();
+ float t = unlikely (s0 == s1) ? 0.f : (target_size - s0) / (s1 - s0);
+ return t * trackTableEntry.get_value (base, idx + 1, sizes) +
+ (1.f - t) * trackTableEntry.get_value (base, idx, sizes);
+ }
+
+ int get_tracking (const void *base, float ptem) const
+ {
+ /*
+ * Choose track.
+ */
+ const TrackTableEntry *trackTableEntry = nullptr;
+ unsigned int count = nTracks;
+ for (unsigned int i = 0; i < count; i++)
+ {
+ /* Note: Seems like the track entries are sorted by values. But the
+ * spec doesn't explicitly say that. It just mentions it in the example. */
+
+ /* For now we only seek for track entries with zero tracking value */
+
+ if (trackTable[i].get_track_value () == 0.f)
+ {
+ trackTableEntry = &trackTable[i];
+ break;
+ }
+ }
+ if (!trackTableEntry) return 0.;
+
+ /*
+ * Choose size.
+ */
+ unsigned int sizes = nSizes;
+ if (!sizes) return 0.;
+ if (sizes == 1) return trackTableEntry->get_value (base, 0, sizes);
+
+ hb_array_t<const HBFixed> size_table ((base+sizeTable).arrayZ, sizes);
+ unsigned int size_index;
+ for (size_index = 0; size_index < sizes - 1; size_index++)
+ if (size_table[size_index].to_float () >= ptem)
+ break;
+
+ return roundf (interpolate_at (size_index ? size_index - 1 : 0, ptem,
+ *trackTableEntry, base));
+ }
+
+ bool sanitize (hb_sanitize_context_t *c, const void *base) const
+ {
+ TRACE_SANITIZE (this);
+ return_trace (likely (c->check_struct (this) &&
+ sizeTable.sanitize (c, base, nSizes) &&
+ trackTable.sanitize (c, nTracks, base, nSizes)));
+ }
+
+ protected:
+ HBUINT16 nTracks; /* Number of separate tracks included in this table. */
+ HBUINT16 nSizes; /* Number of point sizes included in this table. */
+ LNNOffsetTo<UnsizedArrayOf<HBFixed>>
+ sizeTable; /* Offset from start of the tracking table to
+ * Array[nSizes] of size values.. */
+ UnsizedArrayOf<TrackTableEntry>
+ trackTable; /* Array[nTracks] of TrackTableEntry records. */
+
+ public:
+ DEFINE_SIZE_ARRAY (8, trackTable);
+};
+
+struct trak
+{
+ static constexpr hb_tag_t tableTag = HB_AAT_TAG_trak;
+
+ bool has_data () const { return version.to_int (); }
+
+ bool apply (hb_aat_apply_context_t *c) const
+ {
+ TRACE_APPLY (this);
+
+ hb_mask_t trak_mask = c->plan->trak_mask;
+
+ const float ptem = c->font->ptem;
+ if (unlikely (ptem <= 0.f))
+ return_trace (false);
+
+ hb_buffer_t *buffer = c->buffer;
+ if (HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction))
+ {
+ const TrackData &trackData = this+horizData;
+ int tracking = trackData.get_tracking (this, ptem);
+ hb_position_t offset_to_add = c->font->em_scalef_x (tracking / 2);
+ hb_position_t advance_to_add = c->font->em_scalef_x (tracking);
+ foreach_grapheme (buffer, start, end)
+ {
+ if (!(buffer->info[start].mask & trak_mask)) continue;
+ buffer->pos[start].x_advance += advance_to_add;
+ buffer->pos[start].x_offset += offset_to_add;
+ }
+ }
+ else
+ {
+ const TrackData &trackData = this+vertData;
+ int tracking = trackData.get_tracking (this, ptem);
+ hb_position_t offset_to_add = c->font->em_scalef_y (tracking / 2);
+ hb_position_t advance_to_add = c->font->em_scalef_y (tracking);
+ foreach_grapheme (buffer, start, end)
+ {
+ if (!(buffer->info[start].mask & trak_mask)) continue;
+ buffer->pos[start].y_advance += advance_to_add;
+ buffer->pos[start].y_offset += offset_to_add;
+ }
+ }
+
+ return_trace (true);
+ }
+
+ bool sanitize (hb_sanitize_context_t *c) const
+ {
+ TRACE_SANITIZE (this);
+
+ return_trace (likely (c->check_struct (this) &&
+ version.major == 1 &&
+ horizData.sanitize (c, this, this) &&
+ vertData.sanitize (c, this, this)));
+ }
+
+ protected:
+ FixedVersion<>version; /* Version of the tracking table
+ * (0x00010000u for version 1.0). */
+ HBUINT16 format; /* Format of the tracking table (set to 0). */
+ OffsetTo<TrackData>
+ horizData; /* Offset from start of tracking table to TrackData
+ * for horizontal text (or 0 if none). */
+ OffsetTo<TrackData>
+ vertData; /* Offset from start of tracking table to TrackData
+ * for vertical text (or 0 if none). */
+ HBUINT16 reserved; /* Reserved. Set to 0. */
+
+ public:
+ DEFINE_SIZE_STATIC (12);
+};
+
+} /* namespace AAT */
+
+
+#endif /* HB_AAT_LAYOUT_TRAK_TABLE_HH */
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